Good article below from VeloNews on Brand-new designs in road brakes.
This article crosses over to the troubles John had along with the under-the-bottom-bracket on his Madone. Despite the fact that that was eventually shown to be a defective brake (and was a different design), the article above concludes that there’s no sound reason for mounting a brake underneath the bike.
"The only thing that belongs under the chainstays is nothing. Nothing belongs there."
Brand-new rim brake designs are important because the pro’s are going to be slow to adopt disc brakes — if they ever do. There are too numerous troubles to contend with: the speed of wheel changes, the challenges of providing neutral support, and exactly what happens in a crash when a nearly red-hot brake disc slices into someone’s calf.